In a heat pump that has been known to date, an oil separator collects refrigerating machine oil (oil) included in refrigerant discharged from a compressor and the collected oil is returned to the compressor. For example, a heat pump described in Patent Literature 1 (PTL 1) includes an oil return channel for returning oil collected by an oil separator to a compressor. The oil return channel includes a shut-off valve and a capillary. The oil return channel is provided with a pressure sensor that detects an oil pressure in a portion of the oil return channel at an oil separator side relative to the capillary. The heat pump described in PTL 1 is configured to detect an abnormality of the oil return channel such as breakage or clogging by comparing the pressure detected by the pressure sensor with a discharge pressure or a suction pressure of the compressor.